1. Field of the Invention
The invention relates to photovoltaic cells and in particular to such cells which have been modified by depositing on an exposed semiconductor surface thereof, a layer of a porphyrinic compound. Such modified cells have markedly enhanced power output characteristics as compared with the unmodified cells. The invention also relates to methods for producing such modified cells.
2. Prior Art
Photovoltaic cells, as well as their construction, use and theory of operation are known. Generally, these cells comprise a light sensitive semiconductor material, for example, Se, CdS, Si or the like, which, upon being irradiated with light, will produce an electric current that is related to the intensity and wavelength of the source of irradiation. Thus, semiconductor materials and cells made therefrom are a valuable source of energy, and in fact, such cells, also known as solar cells, are presently in use in a wide variety of applications where energy sources are scarce and sunlight is plentiful. The voltage and current, and hence the power output of these cells is severely restricted by the nature and size of the cells as well as the intensity of the available light. Accordingly, any enhancement in the power output of such cells would be most desirable and would constitute a valuable advance in the art.
I have been experimenting with the physical effects of the class of chemical substances known as porphyrins and the present invention is a result of that experimentation. The porphyrins are, of course, well known. There are numerous natural porphyrins and the literature abounds with references to the synthesis of both natural and previously unknown porphyrins.
The present invention represents the application of a newly discovered interaction of the porphyrins to the known properties of photovoltaics, the result being a remarkable and wholly unexpected enhancement of the power output capability of the known photovoltaics.